Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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  • Article
    Citation - WoS: 6
    Citation - Scopus: 6
    Effect of Ammonia on Cobalt Fischer-Tropsch Synthesis Catalysts: a Surface Science Approach
    (Royal Society of Chemistry, 2019) Kızılkaya, Ali Can; Niemantsverdriet, J. W.; Weststrate, C. J.
    Ammonia adsorption and decomposition on defect-rich hcp-Co(0001) surfaces were investigated under ultra-high vacuum conditions in order to provide a fundamental explanation for industrially observed ammonia poisoning of cobalt based Fischer-Tropsch synthesis (FTS) catalysts. Temperature-programmed desorption, infrared spectroscopy and work function measurements indicate that undercoordinated sites bind ammonia stronger than sites on flat Co(0001), and they also induce its dehydrogenation. Density functional theory calculations were employed to explore the reactivity of defective Co surfaces using the fcc-Co(211) as a model. The results indicate that the decomposition products (NH x ) adsorb strongly on or around the step site on fcc-Co(211). We find that NH (+2H ad ), adsorbed in the threefold site on the upper terrace, is equally stable as NH 2 (+H ad ), adsorbed in the bridge position at the step edge, both being significantly more stable than the equivalent species adsorbed on the flat Co(0001). The calculated activation barriers for NH 3,ad dehydrogenation steps are in reasonable agreement with the barriers obtained by fitting experimental data. Based on these fundamental insights, poisoning of cobalt nanoparticles during FTS by NH 3 contaminants can be linked mainly to the blocking of undercoordinated sites by strongly adsorbed NH 2 species.
  • Article
    Citation - WoS: 2
    Citation - Scopus: 3
    The Amido and Bisalkoxo-Complexes of [tri(3,5-Dimethylpyrazolyl)borato]molydenum Nitrosyl
    (TÜBİTAK, 1998) Topaloğlu, Işıl
    In this study, the amido nitrosyl molybdenum complex, [Mo{HM(3,5-Me2C3HN2)3}(NO)Cl(NH 2)], was prepared. This compound reacts with alocohols, yielding the bisalkoxo complexes, [Mo{HM(3,5-Me2C3HN2)3}(NO)(OR) 2] (R = Me, Et, Prn, Bun). The new complexes were analyzed by IR and 1H-NMR spectroscopy.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 2
    Synthesis and Characterization of Amido and Amido(monoalkylamido)nitrosyl-[tris(3,5 Complexes
    (Marcel Dekker Inc., 1997) Topaloğlu, Işıl; McCleverty, Jon A.
    The chloro-amido complex [Mo{HB(3,5-Me2C3HN2)3}(NO)Cl(NH 2)] was prepared by treating [Mo{HB(3,5-Me2C3HN2)3}(NO)Cl 2] with an excess of ammonia. The monoalkylamido complexes [Mo{HB(3,5-Me2C3HN2)3}-(NO)(NH 2)(NHR)] (R = Me, Et, Pr-n and Bu-n) were obtained by the reaction of [Mo{HB(3,5-Me2C3HN2)3}(NO)Cl(NH 2)] with the appropriate primary amines. The IR and 1H NMR spectra of the new complexes were investigated.